Cathode active material for lithium secondary battery and lithium secondary battery including the same

Abstract

The present disclosure relates to a cathode active material for a lithium secondary battery and a lithium secondary battery including the same. A cathode active material for a lithium secondary battery according to embodiments of the present disclosure includes lithium-nickel-based metal oxide particles having a FWHM ratio of 2000% or less, as measured by in-situ X-ray diffraction (XRD) and defined by a specific equation.

What is claimed is: 
     
         1 . A cathode active material for a lithium secondary battery, comprising lithium-nickel-based metal oxide particles having an FWHM ratio of 2000% or less, as measured by in-situ x-ray diffraction (XRD) and defined by Equation 1 below: 
       
         
           
             
               
                 
                   
                     
                       FWHM 
                       ⁢ 
                           
                       ratio 
                       ⁢ 
                           
                       
                         ( 
                         % 
                         ) 
                       
                     
                     = 
                     
                       100 
                       × 
                       
                         ( 
                         
                           
                             
                               FWHM 
                               max 
                             
                             ( 
                             107 
                             ) 
                           
                           / 
                           
                             
                               FWHM 
                               min 
                             
                             ( 
                             107 
                             ) 
                           
                         
                         ) 
                       
                     
                   
                 
                 
                   
                     [ 
                     
                       Equation 
                       ⁢ 
                           
                       1 
                     
                     ] 
                   
                 
               
             
           
         
         (in Equation 1, FWHM max (107) is the maximum FWHM value of a (107) plane peak of the lithium-nickel-based metal oxide particles measured by in-situ XRD, and FWHM min (107) is the minimum FWHM value of the (107) plane peak of the lithium-nickel-based metal oxide particles measured by in-situ XRD). 
       
     
     
         2 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein the FWHM ratio is 1000% to 2000%. 
     
     
         3 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein the FWHM ratio is 1500% to 1900%. 
     
     
         4 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein FWHM max (107) in Equation 1 is 3.7 or less. 
     
     
         5 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein FWHM max (107) in Equation 1 is 3.5 or less. 
     
     
         6 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein FWHM min (107) in Equation 1 is 0.175 or more. 
     
     
         7 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein FWHM min (107) in Equation 1 is 0.185 or more. 
     
     
         8 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein changes in the FWHM value of the (107) plane peak of the lithium-nickel-based metal oxide particles during charging and discharging of the lithium secondary battery are measured in real time using in-situ XRD. 
     
     
         9 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein the lithium-nickel-based metal oxide particles comprise two or more types of doping elements. 
     
     
         10 . The cathode active material for a lithium secondary battery according to  claim 1 , wherein the lithium-nickel-based metal oxide particles have a structure represented by Formula 2 below: 
       
         
           
           
               
               
           
         
         (in Formula 2, M1 and M2 each comprise at least one of Ti, Zr, Al, Mg and W, and 0.8<x<1.5, 0.5≤a≤0.98, 0.02≤b+c≤0.50, 0.02≤c≤0.30, 0<d+e≤0.05, 0.98≤a+b+c≤1.02, −0.1≤y≤0.1). 
       
     
     
         11 . The cathode active material for a lithium secondary battery according to  claim 10 , wherein the molar ratio (d/e) of M1 to M2 in Formula 2 is 0.05≤d/e≤5.5. 
     
     
         12 . The cathode active material for a lithium secondary battery according to  claim 10 , wherein the molar ratio (d/e) of M1 to M2 in Formula 2 is 1.25≤d/e≤3. 
     
     
         13 . A lithium secondary battery comprising:
 a cathode comprising the cathode active material for a lithium secondary battery according to  claim 1 ; and   an anode disposed opposite to the cathode.